Actuator of camera module

Abstract

An actuator of a camera module includes a magnet, a coil facing the magnet, a driver configured to apply a driving signal to the coil to move the magnet in a direction, and a position estimator. The position estimator is configured to convert an oscillation signal into a digital signal in a delta sigma modulation scheme, and estimate the position of the magnet from the digital signal. A frequency of the oscillation signal varies based on a position of the magnet.

What is claimed is: 
     
       1. An actuator of a camera module, comprising:
 a magnet; 
 a coil facing the magnet; 
 a driver configured to apply a driving signal to the coil to move the magnet in a direction; and 
 a position estimator configured to convert an oscillation signal into a digital signal in a delta sigma modulation scheme, sequentially calculate frequency information of the oscillation signal by sequentially delaying a point in time of a calculation period for the digital signal per reference time, and estimate the position of the magnet based on the frequency information, wherein a frequency of the oscillation signal varies based on a position of the magnet. 
 
     
     
       2. The actuator of  claim 1 , wherein the position estimator comprises:
 a frequency divider configured to output a divided signal generated by dividing the oscillation signal by a dividing ratio based on the digital signal; and 
 a quantizer configured to output the digital signal based on a comparison between the divided signal and a reference signal. 
 
     
     
       3. The actuator of  claim 2 , wherein the reference signal and the dividing ratio are set based on a range in which the frequency of the oscillation signal changes. 
     
     
       4. The actuator of  claim 1 , wherein the position estimator is configured to accumulate bit values of the digital signal during the calculation period to calculate the frequency information of the oscillation signal. 
     
     
       5. The actuator of  claim 1 , wherein the position estimator is configured to estimate the position of the magnet using position information of the magnet corresponding to the frequency information of the oscillation signal. 
     
     
       6. The actuator of  claim 1 , wherein the position estimator comprises
 an oscillation circuit configured to generate the oscillation signal, wherein the oscillation circuit comprises an inductor configured to determine the frequency of the oscillation signal. 
 
     
     
       7. The actuator of  claim 6 , wherein the inductor is disposed within a range of a magnetic field of the magnet. 
     
     
       8. The actuator of  claim 1 , wherein the position estimator comprises:
 a converter configured to sample the oscillation signal at a frequency of a reference signal, quantize the sampled signal as a single bit, and output the quantized signal as the digital signal. 
 
     
     
       9. The actuator of  claim 8 , wherein the position estimator comprises:
 a calculator configured to receive the digital signal, and accumulate the bit values of the digital signal during the calculation period to calculate the frequency information of the oscillation signal. 
 
     
     
       10. An actuator of a camera module comprising:
 a magnet; 
 a coil facing the magnet; 
 a driver configured to apply a driving signal to the coil to move the magnet in a direction; and 
 a position estimator comprising an inductor and a converter configured to convert an oscillation signal that changed based on a position of the magnet into a digital signal, and configured to sequentially calculate frequency information of the oscillation signal by sequentially delaying a point in time of a calculation period for the digital signal per reference time and estimate the position of the magnet based on the frequency information, wherein a frequency of the oscillation signal is based on an inductance of the inductor. 
 
     
     
       11. The actuator of  claim 10 , wherein the position estimator comprises:
 a frequency divider configured to output a divided signal generated by dividing the oscillation signal by a dividing ratio based on the digital signal; and 
 a quantizer configured to output the digital signal corresponding to a comparison between the divided signal and a reference signal. 
 
     
     
       12. The actuator of  claim 10 , wherein the position estimator is configured to accumulate bit values of the digital signal during the calculation period to calculate the frequency information of the oscillation signal. 
     
     
       13. The actuator of  claim 10 , wherein the position estimator is configured to estimate the position of the magnet using position information of the magnet corresponding to the frequency information of the oscillation signal. 
     
     
       14. The actuator of  claim 10 , wherein the position estimator comprises:
 a converter configured to sample the oscillation signal at a frequency of a reference signal, quantize the sampled signal as a single bit, and output the quantized signal as the digital signal. 
 
     
     
       15. The actuator of  claim 14 , wherein the position estimator comprises:
 a calculator configured to receive the digital signal, and accumulate the bit values of the digital signal during the calculation period to calculate the frequency information of the oscillation signal. 
 
     
     
       16. The actuator of  claim 1 , wherein the position estimator comprises:
 a first calculator configured to accumulate first bit values of the digital signal for a first calculation period at a first measuring point in time, and to calculate first frequency information of the oscillation signal based on the first bit values; and 
 a second calculator configured to accumulate second bit values of the digital signal for a second calculation period at a second measuring point in time delayed from the first measuring point in time by the reference time, and to calculate second frequency information of the oscillation signal based on the second bit values, 
 wherein the position estimator is configured to output the first frequency information and the second frequency information as the frequency information.